1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
|
/*
* w1-gpio - GPIO w1 bus master driver
*
* Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/w1-gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/of_platform.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/delay.h>
#include <linux/w1.h>
static u8 w1_gpio_set_pullup(void *data, int delay)
{
struct w1_gpio_platform_data *pdata = data;
if (delay) {
pdata->pullup_duration = delay;
} else {
if (pdata->pullup_duration) {
/*
* This will OVERRIDE open drain emulation and force-pull
* the line high for some time.
*/
gpiod_set_raw_value(pdata->gpiod, 1);
msleep(pdata->pullup_duration);
/*
* This will simply set the line as input since we are doing
* open drain emulation in the GPIO library.
*/
gpiod_set_value(pdata->gpiod, 1);
}
pdata->pullup_duration = 0;
}
return 0;
}
static void w1_gpio_write_bit(void *data, u8 bit)
{
struct w1_gpio_platform_data *pdata = data;
gpiod_set_value(pdata->gpiod, bit);
}
static u8 w1_gpio_read_bit(void *data)
{
struct w1_gpio_platform_data *pdata = data;
return gpiod_get_value(pdata->gpiod) ? 1 : 0;
}
#if defined(CONFIG_OF)
static const struct of_device_id w1_gpio_dt_ids[] = {
{ .compatible = "w1-gpio" },
{}
};
MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);
#endif
static int w1_gpio_probe(struct platform_device *pdev)
{
struct w1_bus_master *master;
struct w1_gpio_platform_data *pdata;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
/* Enforce open drain mode by default */
enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN;
int err;
if (of_have_populated_dt()) {
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
/*
* This parameter means that something else than the gpiolib has
* already set the line into open drain mode, so we should just
* driver it high/low like we are in full control of the line and
* open drain will happen transparently.
*/
if (of_get_property(np, "linux,open-drain", NULL))
gflags = GPIOD_OUT_LOW;
pdev->dev.platform_data = pdata;
}
pdata = dev_get_platdata(dev);
if (!pdata) {
dev_err(dev, "No configuration data\n");
return -ENXIO;
}
master = devm_kzalloc(dev, sizeof(struct w1_bus_master),
GFP_KERNEL);
if (!master) {
dev_err(dev, "Out of memory\n");
return -ENOMEM;
}
pdata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags);
if (IS_ERR(pdata->gpiod)) {
dev_err(dev, "gpio_request (pin) failed\n");
return PTR_ERR(pdata->gpiod);
}
pdata->pullup_gpiod =
devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW);
if (IS_ERR(pdata->pullup_gpiod)) {
dev_err(dev, "gpio_request_one "
"(ext_pullup_enable_pin) failed\n");
return PTR_ERR(pdata->pullup_gpiod);
}
master->data = pdata;
master->read_bit = w1_gpio_read_bit;
gpiod_direction_output(pdata->gpiod, 1);
master->write_bit = w1_gpio_write_bit;
/*
* If we are using open drain emulation from the GPIO library,
* we need to use this pullup function that hammers the line
* high using a raw accessor to provide pull-up for the w1
* line.
*/
if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN)
master->set_pullup = w1_gpio_set_pullup;
err = w1_add_master_device(master);
if (err) {
dev_err(dev, "w1_add_master device failed\n");
return err;
}
if (pdata->enable_external_pullup)
pdata->enable_external_pullup(1);
if (pdata->pullup_gpiod)
gpiod_set_value(pdata->pullup_gpiod, 1);
platform_set_drvdata(pdev, master);
return 0;
}
static int w1_gpio_remove(struct platform_device *pdev)
{
struct w1_bus_master *master = platform_get_drvdata(pdev);
struct w1_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
if (pdata->enable_external_pullup)
pdata->enable_external_pullup(0);
if (pdata->pullup_gpiod)
gpiod_set_value(pdata->pullup_gpiod, 0);
w1_remove_master_device(master);
return 0;
}
static int __maybe_unused w1_gpio_suspend(struct device *dev)
{
struct w1_gpio_platform_data *pdata = dev_get_platdata(dev);
if (pdata->enable_external_pullup)
pdata->enable_external_pullup(0);
return 0;
}
static int __maybe_unused w1_gpio_resume(struct device *dev)
{
struct w1_gpio_platform_data *pdata = dev_get_platdata(dev);
if (pdata->enable_external_pullup)
pdata->enable_external_pullup(1);
return 0;
}
static SIMPLE_DEV_PM_OPS(w1_gpio_pm_ops, w1_gpio_suspend, w1_gpio_resume);
static struct platform_driver w1_gpio_driver = {
.driver = {
.name = "w1-gpio",
.pm = &w1_gpio_pm_ops,
.of_match_table = of_match_ptr(w1_gpio_dt_ids),
},
.probe = w1_gpio_probe,
.remove = w1_gpio_remove,
};
module_platform_driver(w1_gpio_driver);
MODULE_DESCRIPTION("GPIO w1 bus master driver");
MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
MODULE_LICENSE("GPL");
|
